We performed sub-analyses on the data from the MEGA (Management of Elevated Cholesterol in the Primary Prevention Group of Adult Japanese), a large randomized controlled trial of lipid-lowering treatment with pravastatin for primary prevention of cardiovascular events in 7,832 patients with mild to moderate hypercholesterolemia. The main analysis of the MEGA Study showed that reducing low-density lipoprotein cholesterol level by 18% with pravastatin was associated with a significant 30% reduction in coronary heart disease and 35% reduction in stroke incidence at 5 years of follow-up. In a sub-analysis on 5,356 women, women aged 60 years or more who were treated with diet plus pravastatin had a markedly higher risk reduction by 64% for stroke than did women treated with diet alone. The results of sub-analyses on both 2,110 diabetic and 3,277 hypertensive patients indicated that risk reduction with pravastatin was more substantial in cerebral infarction than in coronary heart disease (57% versus 32% and 46% versus 29%, respectively). These results indicated that pravastatin treatment can prevent stroke in post menopausal women as well as men, and do so more than coronary heart disease in diabetic and hypertensive Japanese patients with hypercholesterolemia. The Proportion of Treatment Effect (PTE) analysis suggests that such effects are related to pleiotropic effects beyond cholesterol-lowering effect more in stroke prevention than in prevention of coronary heart disease.